1. Nutrient Pot Preparation
Prepare nutrient pots of appropriate specifications based on the blueberry species, variety, and time of nursery release for commercial seedlings. For one-year-old commercial seedlings, use 10cm × 10cm nutrient pots. For two-year-old commercial seedlings, use 12cm × 12cm nutrient pots. If nutrient pots have been used previously, they should be cleaned and dried, then disinfected by soaking in a 500-fold solution of 50% thiabendazole wettable powder for 12 hours; or by soaking in a 1000-fold solution of 10% potassium permanganate for 0.5 hours, followed by rinsing and drying for later use.
2. Preparation and Treatment of Nutrient Medium
The nutrient medium should be a loose, well-aerated composite medium with high organic matter content. Following the principle of using locally available materials, the nutrient medium can be prepared using a mixture of loam, larch needles, and peat moss in a 1:1:1 ratio, or loam and well-decomposed organic matter (such as larch needles, sawdust, straw, or weeds) in a 2:1 ratio. This mixture is suitable for blueberry root growth and is cost-effective.
The prepared substrate must undergo disinfection and acidification treatment before use. Mix or spray the substrate with thiabendazole to ensure the substrate’s relative humidity reaches 50%-60%. Cover with plastic film and seal for fumigation. Then remove the film and sun-dry for 3-5 days to allow residual gases to evaporate before undergoing acidification treatment. Different varieties have varying pH requirements, with the optimal pH range generally being 4.3-4.8. Under suitable temperature and humidity conditions in the greenhouse, sulfur takes 15-20 days to take effect, with the lowest pH value appearing after 30-40 days. The role of sulfur in substrate acidification is a complex process closely related to substrate moisture and temperature. Under scientific water and fertilizer management conditions, the above treatment during the nutrient pot seedling stage can ensure that the substrate pH value remains within the plant’s required range.
3. Transplanting
Blueberry roots are very fragile and easily damaged during transplanting, with slow recovery afterward. Therefore, improper transplanting not only lowers survival rates but also slows growth of surviving seedlings, reducing the rate of mature plants in the same year.
Transplanting should preferably be done in late autumn or early winter, though spring transplanting before bud break is also acceptable. To minimize transplanting’s impact on growth vigor, as much bed soil as possible should be retained during transplanting. If the nursery has good automatic irrigation conditions, transplanting can also be done during the growing season if necessary.
To ensure standardized operations, first fill the pots with an appropriate amount of nutrient medium, arrange them neatly at a certain width, ensure appropriate density, and arrange them in rows and columns with an equal number of pots per row for production statistics. Before transplanting, thoroughly water the nutrient medium in the pots. After the water has settled, plant the seedlings in holes made in the center of the medium, with a hole depth of 1–1.5 cm being optimal. After planting, seal the holes tightly, watering continuously as you plant, and water in multiple stages until the medium is saturated. Seedlings planted on the same day must be watered to saturation on the same day. Any fallen seedlings should be straightened, and a small cover should be placed over them, with a shade net on the outside to promote root establishment. It is important to note that when removing seedlings from the acclimatization bed, care should be taken not to damage the root system, which may retain some substrate. From the time the seedlings are removed from the hardening bed until transplantation, the root system must remain consistently moist. Before potting, spray the roots with an appropriate amount of water, and during summer, spray the entire plant with water. During high-temperature seasons, ensure proper ventilation and cooling for the seedlings, avoid direct sunlight, and prevent overheating. Do not remove too many seedlings at once. Weak seedlings that cannot be potted should be promptly replanted in the hardening-off bed for continued care.
The transplanting depth should generally be the same as or slightly deeper than the depth in the propagation bed, ensuring that the soil can cover the root system and stabilize the seedlings.
4. Post-transplant management
(1) Light management: Use diffused light as the primary light source. To ensure transplant survival rates, provide appropriate shade based on different light periods. For the first 10 days after transplanting, use a movable shade net with 90% shading on sunny days to shorten the acclimatization period. When the greenhouse temperature exceeds 25°C, shade nets should be used for shading. As the plants grow, light intensity should be gradually increased, and the shade nets can be removed after the transplanted seedlings have acclimatized.
(2) Temperature Management: From transplanting to acclimatization, the daytime air temperature in the greenhouse should be maintained at 25°C to facilitate root growth. Once new shoots grow and new leaves form, it indicates that acclimatization has ended. After acclimatization, daytime temperatures should be controlled between 20–25°C. When the greenhouse temperature reaches 28°C, ventilation openings should be opened gradually in stages; when temperatures drop below 25°C, ventilation openings should be closed, gradually reducing their size until fully closed, to maintain the greenhouse temperature between 25–28°C, with nighttime temperatures above 13°C.
(3) Water Management: The key points of water management are to supply water in a timely, appropriate, and regular manner, ensuring both the physiological needs of the root system and facilitating the acidification effect of sulfur in the substrate. Excessive water supply inhibits root growth, causes acidity in the substrate to leach out, and fails to maintain an appropriate pH value during the later stages of seedling cultivation; insufficient water supply leads to overly dry substrate, impairs root physiological functions, and may even cause root death, resulting in a slow acidification effect of sulfur. Generally, watering is done every 2–3 days, with the frequency adjusted according to climate and substrate moisture conditions. Each watering should provide enough moisture so that water slightly seeps out of the drainage holes at the bottom of the pot. The water should have a neutral or slightly acidic pH and preferably be soft water. In production, if the substrate acidity is within the appropriate range, the water quality mentioned above does not need to be acidified and can be applied directly. Water management remains crucial after transplanting and establishment. The relative air humidity should not be less than 70%. Higher air humidity is beneficial for seedling establishment and plant growth. The soil should be kept moist but not overly wet. Each watering should be thorough, and watering should be repeated when the nutrient substrate on the surface of the pot dries out, following the principle of alternating between dry and wet surfaces of the nutrient substrate within the pot. In areas prone to water deficiency, such as near windbreaks, timely supplementation with a spray bottle is necessary.
(4) Fertilization management: To achieve a certain quality of seedlings, proper fertilization is a key factor. The fertilization ratio must be appropriate, with a nitrogen, phosphorus, and potassium ratio of 1:0.5:1 being optimal. The total application rate of compound fertilizer per plant per application should be approximately 3g. The number of fertilization applications can be adjusted based on actual needs. During a growing season, fertilization can be applied 1–4 times. Avoid over-applying nitrogen fertilizer, especially in the fall, as this can lead to excessive shoot and leaf growth, delay dormancy, and weaken cold tolerance.
(5) Weed control: Weeds grow much faster and have greater vitality than blueberry seedlings. If weeds are not removed promptly, the quality and survival rate of the seedlings will be affected. Especially in good soil conditions with adequate fertilizer and water, weed control becomes even more important. Timely manual weed removal promotes soil aeration and root growth.
(6) Plant management: Before the basal buds form branches, pruning is generally avoided to maximize leaf area, accumulate nutrients, and promote root growth and basal bud emergence. Once clump-like branches form, lower weak branches should be thinned to improve ventilation and light penetration, thereby promoting the growth of robust branches. During the early to mid-stage of nutrient pot seedling cultivation, growth is relatively weak. To stimulate physiological activity, spray with a 1.6% amine ester solution or a 0.04% brassinosteroid solution diluted 1,200–1,500 times, with a 7-day interval between applications. During the initial planting stage, to promote rooting and acclimatization, spray 1–2 times with 98% indole butyric acid powder at 10–40 mg/kg. After acclimatization, to promote shoot growth, lateral branch budding, and basal bud emergence, spray 2–3 times with 40% gibberellic acid granules at 20–25 mg/kg.
(7) Pest and disease control: Major diseases include gray mold, root (stem) rot, and branch wilt, while major pests include aphids.
Gray mold occurs during the early stages of transplantation, as low temperatures and high humidity in the early stages make the disease highly likely to occur and cause severe damage. Symptoms include gray mold-like substances on various parts of the plant, with severe cases resulting in the death of the entire plant. Use a 40% imidacloprid suspension at 800-1200 times dilution or a 25% amoxicillin suspension at 1000-1500 times dilution, spraying once every 7-10 days for 2-3 consecutive applications.
Root (stem) rot occurs during the early stages of transplanting, affecting the roots or the stem near the substrate. In severe cases, it can cause the entire plant to die. For prevention and control, first disinfect the substrate and maintain a relatively stable substrate moisture level. Use a 4% pyrimidine nucleoside antibiotic solution at a dilution of 1000-1500 times, or a 10% polyoxin wettable powder solution at a dilution of 1000-1500 times for root drenching.
Branch wilt disease primarily occurs during the mid-to-late stages, with the tips of new shoots (branches) necrotizing and the infection spreading downward along the stem, eventually causing the entire plant to die. Regular applications of protective pesticides can be made, such as a 1,500-fold dilution of 25% pyraclostrobin suspension or a 1,500-fold dilution of 70% thiophanate-methyl wettable powder.
Aphids primarily damage new shoots and can transmit viral diseases. Once an infestation occurs, prompt control measures must be taken. Spray with 10% imidacloprid wettable powder at 1,500–2,000 times dilution; 4.5% cypermethrin emulsifiable concentrate at 1,500–2,500 times dilution; or 1.8% avermectin emulsifiable concentrate at 2,000–3,000 times dilution, etc.
Post time: Aug-20-2025